Apparatus for printing bags

ABSTRACT

Apparatus, for printing information on a paper bag, featuring a mechanism for raising a printing arm after a bag is printed, pivoting the arm in an arc to another position, and then actuating the arm toward an ink pad so that the printing plate contacts the pad. The cycles of operation are preferably sequentially timed with the operation of a device for stripping one bag at a time from a stack of bags.

United States Patent 1191 Thomson et al.

[ Nov. 13, 1973 [54] APPARATUS FOR PRINTING BAGS 3,635,154 1/1972 Geryet a1. 101/334 X 3,599,566 8/1971 Flsh 101/333 [75] Invent: Ely Thom;Clyde 3,216,352 11/1965 Schnackel 101/333 Sailors, Jr., both of Houston,Tex.

[73] Assign: 32: 3: r i s Company Primary Examiner-Edgar S. BurrAssistant ExaminerClifford D. Crowder [22] Filed: Dec. 11, 1972Attorney-Jerry B. Peterson et a1.

[21] App]. No.: 314,042

Related U.S. Application Data ABSTRACT [62] Division of Ser. No.154,529, June 18, 1971, Y

abando'wd- Apparatus, for printing information on a paper bag, featuringa mechanism for raising a printing arm after [52] U.S. Cl 101/334,101/44, 271/131 a bag is printed, pivoting the arm in an arc to another[51] Int. Cl B411 17/00 position, and then actuating the arm toward anink [58] Fleld of Search 101/3331 pad so that the printing platecontacts the pad. The 101/105 44 cycles of operation are preferablysequentially timed with the operation of a device for stripping one bagat [56] References a time from a stack of bags.

UNITED STATES PATENTS 3,307,479 3/1967 Messmer 101/334 8 Claims, 7Drawing Figures FLA-Bl 57 I 7M1 Y P11111111 60 Ru mm v 66 II i I so 1 ias 1' 1' 67 59 M. ,u H 5 61b em L" x 1 s I 63 i 1 3 ,o 5 1 s: 41 5 70 I35 i v 70 72 so a 7 PAIENTEBnuv 13 197a 3771. 448

sum 10F 21 EL) KNOX THOMSON CLYDE A. SAILORS JR. I NVENTORS BY M WMATTORAE' Y ELY KNOX THOMSON CLYDE A. SAILORS JR.

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\EXHAUST TO BAG em INVENTORS Z Fig.7 BY /6 W7 APPARATUS FOR PRINTINGBAGS This is a division of application Ser. No. 154,529, filed June 18,1971, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention isa method and apparatus for stripping one bag at a time from the bottomof a stack of empty paper bags and moving the stripped bag into positionfor a subsequent operation such as the printing of information on thebag. Also included may be apparatus, sequentially timed with operationof the stripper, for automatically printing information on the strippedbag. The stripper-printer combination may be integrated with a bagfilling machines so that one empty bag is stripped and printed each timea bag is filled with product. Altemately, the combination may beoperated as a self-contained unit which will automatically supply themomentary impulse for the beginning of a cycle.

This invention was developed primarily for use in the carbon blackindustry, in which for several years different grades of carbon blackhave been packaged in bags of different colors. This practice is knownas colorcoding. In view of the recent development of many new grades ofcarbon black, the present system, in which each bag is printed by thebag manufacturer with the grade designation, is believed to have becomeobsolete. This invention was developed in order to provide a relativelysimple and economical means of using one color for all bags and forprinting the desired grade and other nomenclature on the bagsimmediately prior to the filling thereof. If desired, the printing mayinclude the use of a set of color-coded inks, either as background or asthe printing type. It will be apparent that the method and apparatus ofthis invention will be applicable to the packaging of products otherthan carbon black.

2. Description of the Prior Art So far as we know there is no prior artdisclosing or similar to our method and apparatus for stripping bagsfrom the bottom of a stack of empty bags.

OBJECTS OF THE INVENTION The objects and advantages of this inventionare as follows:

1. An economical and convenient means to identify material packaged inpaper bags with the proper nomenclature, with or without color-coding.

2. Bag inventories can be reduced by using the same properly sized bagsfor different grades of black or other material.

3. Only those bags actually filled will have identification and printingin the space provided.

4. An interchange of bag supplies between plants during an emergencyshortage can be initiated.

5. Customers can receive shipments from any one of several plants withthe assurance that the bags will be the same color and appearance andthat they will have the proper markings appearing in the identicallocation on each bag.

6. Elimination of the need for printing presses at the plants.

7. Elimination of the possibility of using an improperly-marked bag.

8. Elimination of the possibility of printing the wrong quantity of bagsfor a given quantity of product.

9. Simplicity of manufacture and operation.

SUMMARY OF THE INVENTION One aspect of this invention is a method andapparatus for stripping one bag at a time from the bottom of a stack ofempty paper bags and moving the stripped bag into position for asubsequent operation such as the printing of information or pictorialmatter on the bag. The key element of the stripper is a pick-up memberwhich engages the folded lip of the bottom bag and carries the bagforward into position for the subsequent operation. Another aspect ofthe invention is apparatus, sequentially timed with operation of thestripper, for automatically printing the stripped bag. Thestripper-printer combination may be integrated with a bag fillingmachine so that one empty bag is stripped and printed each time a bag isfilled with product. Alternately, the combination may be operated as aselfcontained unit which will automatically supply the momentary impulsefor the beginning of a cycle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view of theentire combination of stripper and printer;

FIG. 2 is a partial plan view of the combination taken along lines 22 ofFIG. 1;

FIG. 3 is an end elevation view of the combination, taken along thelines 3-3 of FIG. 1;

FIG. 4 is a sectional view of the bag pickup and including a bag, takenalong section lines 4-4 of FIG. 2;

FIG. 5 is a fragmentary sectional view taken along section line 5-5 ofFIG. 2;

FIG. 6 is a view taken along the line 6--6 of FIG. 5;

FIG. 7 is a schematic diagram of the electrical and pneumatic controlcircuits and associated switches, valves, and air cylinders.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic components andoperation of the invention will first be described. Referring to FIGS.l-3, table I, supported by base frame 3, is divided by divider 5 intotwo general sections; namely, a bag-holding and stripping sectiongenerally shown at 7, and a bag printing section 8 on the other side ofdivider 5 and including printer 9. The bags are stacked in thebag-holding section 7, and when the operation is commenced, the bottombag 11 is engaged (at the folded lip 11a) by bag pickup 13, and is movedto the bag printing section by movement of pickup 13, along slot 14 tothe position shown in dotted lines of FIG. 2. When the bag reaches theprinting position, printer 9 automatically prints the desiredidentification on the bag. By means of a switch and air cylinder, pickup13 then returns to its rest position as shown in solid lines in FIG. 2.

Referring to FIGS. 1-6, the construction and operation of the stripperwill now be described in somewhat greater detail.

In order that bags may be stripped from a rather large stack of bagswithout the weight preventing proper stripping, the table 1 ispreferably inclined at an angle with respect to the horizontal so thatpart of the weight of the bags is resting on side panel 15. Thepreferred horizontal is shown in FIG. 3. We prefer to use an angle ofabout 45 although other angles ranging from horizontal up to about canbe used.

The angle of the table, however, has a tendency to cause the bags tocurl up the side of the side panel 15. In order to obviate this curlingaction of the bags on panel 15, we prefer to allow the end a of panel 15to move inwardly against the bags once each cycle by means which will bedescribed below with reference to the description of the electrical andpneumatic control assembly. Of course, this action of panel 15 could beinitiated by purely mechanical means; for example, by a lever actuatedby bracket 17.

Movable tubular bag weight 10 rides on the top of the bag pile to keepthe bottom bag in proper position.

Bag stop 29 is adjustably secured to table 1 as shown.

The movement back and forth of bag pickup 13 is controlled by aircylinder 33 connected by means of pulleys 35 (FIG. 7) to cable 37. Theair supply to cylinder 33 is controlled by micro switches 39 and 41.

Retainer 43 (FIG. 2) is desirably included in order to hold the bags inproper position during printing.

Retainers 45 are desirably included in order to prevent any bags otherthan the bottom bag from moving into the printing position.

Adjustable bag guide bars 47 are desirably included to aid in guidingthe bag to its proper position.

Referring to FIG. 5, the apparatus preferably includes air pipe 49 forsupplying a plurality of air jets through holes or slits 50 in the pipedivider 5. Exhaust air is supplied for this purpose four times eachcycle in order to prevent the bags from sticking together and to takepart of the weight off the bottom bag.

Referring now to FIGS. 1 and 3, the action of the printer 9 will now bedescribed. The printer is mounted within cover plates 57, and theprinter assembly is slideably supported (at 58) by printer mountingframe 59. Referring to FIG. 3, the position of the printer in onedirection can be adjusted by turning lever 60 attached to threaded rod62, after releasing the locking devices 64 by means of levers 66. Theposition of the printer in the other direction is preferably adjustablebecause frame 59 is slideable (at 59a) on angle member 68, afterreleasing locking devic: i 70 by means of levers 72.

The printing plate 61, containing thedesired identification ornomenclature, is pressed against the bag (not shown) on table 1 by meansof downward movement of printing arm 63 actuated by air cylinder 65through rod 67. Rod 67 is pivotally secured to tongue 69 as shown inFIG. 3. After the bag is printed, air cylinder 65 is actuated in theopposite direction, thereby raising the printing arm and pivoting theprinting plate to the position shown at 61a in dotted lines in FIG. 3,and then to the position 61b against printing ink pad 71. The angle ofsuch pivot is about I l0-l40 and preferably about l-l30. A printing armmounting shaft 73 (hidden by spacers 73a in FIG. 1) is secured to coverplates 57 to prevent lateral movement of the arm. Proper movement of theprinting arm so as to provide movement of the printing plate fromposition 61a to 61b is assured by the fact that the outer surface of theprinting arm contacts bearing 75 affixed to a bearing mounting shaft(hidden by spacers 76), which in turn is secured to cover plate 57. Slot78 is included to allow movement of arm 63.

The upper portion of printing arm 63 has a hole drilled down the centerto accommodate a compression spring 77. With no pressure on air cylinder65 and consequently no force on rod 67, the force of spring 77, the

spring being under some compression, forces the bottom of the slot 78into registry with the shaft 73. For proper operation, the staticcompression of spring 77 must be set to overcome the combined weight ofthe arm 63 and the printing plate 61 to maintain the bottom of the slot78 in registry with the shaft 73.

As force is applied to rod 67 by the piston in cylinder 65, the arm 63is restrained between shaft 73 and bearing to impart a linear motion torod 63 and printing plate 61, so that the type on printing plate 61 willmove linearly against the bag or other piece to be printed, rather thanin an arc which would cause smearing of the printing.

As the assembly moves downward, more compression is applied to spring77.

Conversely, when force is applied in the reverse direction on rod 67 bythe piston in cylinder 65 without the spring force applied to arm 63,the arm would tend to move in an arc, since the direction of forceapplied by rod 67 is tangential to the axial line of arm 63. Since theforce applied by the spring is greater than the initial force applied byrod 67, the spring force prevails to move arm 63 in a linear directionaway from the table 1 until the bottom of the slot 78 contacts shaft 73,at which time the force applied through rod 67 exceeds the force appliedby the compression force of spring 77. Since rod 67 is tangential to thelinear axis of arm 63, arm 63 pivots on shaft 73, and arm 63 again movesin an arc toward position 61a. Thus, the function of spring 77 is toexert a linear force upon printing arm 63 in a direction opposite to theforward motion of the arm. By forward motion, we mean motion towardtable 1 or printing ink pad 71. Alternately, a tension spring could bemounted externally of arm 63 to accomplish the same results.

Printing plate 61 is secured to printing arm 63 by means of a screw (notshown), but proper alignment is assured by the use of dowel pins 79passing through holes in the bottom end of the printing arm into contactwith tension springs (not shown).

The necessary control components such as solenoids, air valves,switches, relays, and terminals are mounted to the inside of one of thecover plates 57.

The electrical and pneumatic controls will now be described.

In FIG. 7, the plug is composed of two parts; a male portion 100M and afemale portion 100F which, when connected, have common electricalterminals .1000, 100b, 1000, and 100d. In operation, the terminal 100aof plug 100M is connected to one leg of an AC circuit through a conduitrepresented by a solid line and the terminal 100b of 100M is connectedto the opposite leg of the AC circuit as represented by the dotdashline. Terminals 100d of plugs 100M and 100F are connected to ground.

In the present invention the mechanism can be operated in either of twomodes, namely: (i) controlled by a separate machine (such as abag-filling machine) having an electrical circuit that will provide amomentary impulse of electric current to start the operation, in whichcase terminal 1000 of plug 100 will be connected to the separatemechanism that supplies the electrical impulse, or (ii) it can beoperated as a self-contained unit that will automatically supply themomentary impulse for the beginning of a cycle and will continuouslycycle as long as electric power and air power are supplied to themachine.

The circuit breaker 102 is a three-position switch, center-off as shown.In FIG. 7, the electrical connections in the control side of the circuitare represented by solid lines; the common electric circuit isrepresented by dot-dash lines; and all air conduits are represented bydouble lines. The circuits are drawn to show the standby conditionexcept that with air pressure applied rough through 114 and thencethrough line 116, the supporting means or bracket 17 will move to itsleftmost position (to the left of the position shown in FIG. 7) toactuate the switch 41.

The first mode of operation described will be as specified in mode (i)above in which the present invention operates as a slave to a secondelectro-mechanical device which supplies the mutual electrical impulseto start the cycle. To ready the cirduit for operation, switch 102 isthrown to establish contact between points 102a and 102b, and betweenpoints 102e and 102d, of switch 102. With air applied at the air intakeline 114 and with points 100a, 100b and 1000 of plug 100M connected totheir proper electrical source, the machine is in a standby positionwith air applied through ports 112W and 112X of the four-way air valve112 to control valve 87A (via line 116) and then to port 33a of cylinder33; and air is also supplied through ports 110W and 1 10X of four-wayvalve 110 to control valve 87C (via line 118) and then to port 65a ofcylinder 65. When an electrical impulse is applied through point 1000 ofplug 100, an electrical connection is established through points 102aand 1021) of switch 102 to terminal 106-4 of terminal strip 106 andthence through points 41a and 41b of switch 41 through terminal 106-3 topoint 104a of the solenoid 104a-b of relay 104, since point 104b isconnected to the common leg 1030 of the AC circuit through terminal106-6 and thence through points 390 and 39d of switch 39 and backthrough terminal 106-5 to the common leg 1010 of the electrical circuitthrough point 100b of plug 100. At the instant relay 104 is actuated,the off-delay timer 105 is also actuated, completing a circuit betweenpoint 105 a and 105k. When relay 104 deactuates, offdelay timer 105remains actuated for a pre-set time period and then deactuates, breakingconnection between points 1050 and 10512.

Simultaneously with actuation of relay 104, electrical current isapplied to point 1040 of relay 104 by the jumper wire 104n, and thence,since the relay 104 is actuated, through points 1040 and 104d toterminal 106-7 of terminal strip 106 and thence to point 112a of thesolenoid 112a-b in the four-way air valve 112. This circuit is completedthrough point 1l2b of the air valve 112 through terminal 106-8 andthence through the common leg 1010 to point 100b of plug 100.

When the solenoid 112a-b of the air valve 112 is actuated as indicatedabove; the air valve element 112V shifts position in the directionindicated by the arrow to connect port 112W to port 112Y and port 112Xto port 1122. At this instant, the air inlet 114 is connected throughports 112W and 112Y through line 120, to control valve 873, then to port33b of cylinder 33. This causes the piston 33p to move to the left asshown in FIG. 7, and being connected to cable 37, causes bracket 17 tomove to the right carrying the bag pickup mechanism 13 shown in FIGS. 2and 4 to the left or forward, to engage a bag. In addition air flowsthrough line 121 to port 50a of cylinder 50 causing piston 50? toretract rod 51 which is affixed to the flexible side panel 15 (FIG. 1)of the bag bin. Air is then exhausted through port 50b, into line 122,into line 116, and through pipe 49.

When the bracket 17, FIG. 7, moves to the right sufficiently todeactuate the switch 41, the points 410 and 41d of switch 41 close,establishing a circuit from point a of plug 100 through terminal 106-9,through l02c and jumper wire 102m to point 102f, and by the jumper wire102n to point 102d, and thence through point 102e to terminal 106-1 viawire 108C to 104f, 104h via jumper wire P, through point 104g, viajumper wire 0 to point 104a, to point 1040 via jumper wire n, and thento 104d of relay 104. From point 104d, this current is connected throughterminal 106-7 to the solenoid 1 12a-b of air valve 112, maintainingthis air valve in an actuated condition until bracket 17 moves all theway to the right (FIG. 7) and actuates switch 39 thereby breaking thecontacts 39c and 39d of switch 39 which are in the common return circuit1030 of solenoid 104a104b. This breaking of contacts 390 and 39d thusresults in the relay 104 returning to its normal or deactuatedcondition, thereby closing points 104i and 104j, and points l04f and1040, of relay 104. At this instant the following actions occur:

I. Solenoid 112a-b of air valve 112 is deactuated,

and by spring return the valve element 112V revolves clockwise,connection port 112X with port 112W and port 112Z with port 112Y. Thisresults in air pressure being applied through line 114 through air valve112 and line 116 to port 33a of cylinder 33 causing the piston 33P ofcylinder 33 to move to the right as shown in FIG. 7. Also, air pressureis applied through line 122 to port 50b of cylinder 50 causing piston50? to extend rod 51 which is affixed to the flexible end 15a of the bagbin. Air is then exhausted through port 50a into line 121 which connectsto lines 120, 126, and 49.

2. A circuit is completed between point 100a, through terminal 106-9through points 0, f (via jumper m), d (via jumper n), and e of switch102, to terminal 106-1 and points 104f and 104e of relay 104. Thence thecircuit is completed through points a and 105b of off delay timer 105,then to terminal 106-10, and point a of solenoid 110a-b of air valve110. This circuit is completed from point 11% through terminals 106-11,and then back through the common leg 1010 to point 100b of plug 100.

3. When the solenoid 110a-b is actuated, the valve element 110V of airvalve 110 rotates in the direction of the arrow to connect port 110Wwith port 110Y and port 110X with port 1102. This applies air pressurethrough ports 110W and 1 10Y and line 1 11 to control valve 87D and tothe port 65b of cylinder 65 causing rod 67 to actuate printing plate 61to print the bag positioned by bag pickup 13. Air is also exhaustedthrough port 65a and lines 118 and 124 to pipe 49.

4. The piston 33p of cylinder 33 having moved all the way to the rightwith bracket 17 actuating switch 41, opening contact points 410 and 41dand closing points 41a and 41b. The points 105a and 105b of theoff-delay timer 105 now open after concluding the pre-set delay period,breaking the circuit and deactuating solenoid 110a-b of air valve 110.By spring return the valve element 110v revolves clockwise, connectingport 110W with port 110X and port 1102 with port llY. This applies airpressure through ports 110W and 110X and line 118 to control valve 87Cand to port 65a of cylinder 65 causing rod 67 to actuate and moveprinting plate 61 in position against ink pad 71 as shown in FIG. 3. Airis also exhausted through port 65b and lines 111, 124, and pipe 49.

The speeds of movement of the piston in the cylinders 33 and 65 arecontrolled by the flow control valves 87A, 87B, 87C and 87D. The flowcontrol valves 87 are characterized in that through a ball-checkarrangement there is free flow of air through the valve in the directionopposite the arrow and a variably restricted flow of air in thedirection of the arrow. Since the ports 110Z and 1122 of the air valves110 and 112 are connected to exhaust, by the restriction of air flowthrough the valves 87, the movement of the pistons in cylinders 33 and65 can be controlled by controlling the speed with which the air isexhausted from the cylinders through lines 124 and 126. In this way,together with the electrical circuit, the action of the cylinders issynchronized. This provides a wide latitude in the speeds at which themechanism can be operated, the speed with which bags can be stripped,and the periods of time that the printing plate 61 is in contact withthe ink pad and with the bag to be printed.

Lines 124 and 126 are connected to pipe 49 for the purpose describedpreviously.

The second mode of operation (ii) is fully automatic and is attainedwhen point 100a of plug 100 is connected with the proper electricalvoltages and when the switch 102 is manually closed to connect pointl02b with point l02c and point l02e with point l02f. When point l02b isconnected with point 102:: of switch 102, an electrical circuit isestablished between point 100a of plug 100 through terminal 106-9through points 1020 and l02b and thence through terminal 106-4 throughpoints 41a and 41b of switch 41 to terminal 106-3, to point 104a ofrelay 104, and thence through the solenoid 104a-b through the common leg1030 as previously described. This actuates relay 104 and connectspoints 104C and 104d and points 104g and 104k. The operation of thecircuit from this point forward is identical to that as previouslydescribed; however, each time bracket 17 (FIG. 7) returns to itsleftmost position it reactivates the circuit enabling the machine torepeat the cycle without utilizing an outside momentary electricalimpulse.

While we have thus described the preferred embodiments of the presentinvention, many variations will be suggested to those skilled in theart. The foregoing description and examples should therefore not beconsidered limitative; and all such variations and modifications as arein accord with the principles described are meant to fall within thescope of the appended claims.

We claim: 1

1. A printer comprising:

reciprocal rod actuating means pivotally fixed at a stationary point;

a rod attached at one end to said actuating means and pivotally attachedat the other end to a tongue projecting from the side ofa printing arm,said tongue being located at a point intermediate of the ends of saidprinting arm;

said printing arm having a printing plate attached to one end thereof;

said rod and said printing arm being substantially aligned in one planebut being slightly out of parallel when viewed perpendicular to saidplane when said rod is in its extended position, the angle between saidrod and said arm being convergent in a direction toward said tongue;

said arm being pivotally secured to a fixed point intermediate saidtongue and the opposite end of said arm;

said arm containing a longitudinal slot in which is located a fixedprinting arm shaft, the axis of said shaft being perpendicular to saidarm and parallel to the axis of pivot of both said rod actuating meansand said tongue, said shaft being located at a point intermediate saidtongue and the opposite end of said arm;

a bearing surface mounted on a fixed bearing mounting shaft, saidbearing mounting shaft being parallel to said printing arm shaft andbeing positioned between said rod and said arm at a point intermediatesaid printing arm shaft and the end of said arm opposite the end onwhich said printing plate is affixed;

whereby said printing arm is pivotable from an extended position, atwhich said rod is in its extended position, to a partially retractedposition, at a pivot angle of about 1lO-l40 from said extended position,in which said arm contacts said bearing surface, and whereby said arm ismovable in a straight line along said bearing surface to afully-retracted position; and

a printing ink pad in a fixed position, said position being located sothat said printing plate contacts said pad when said arm reaches saidfully-extended position.

2. The printer of claim 1 in which said pivot angle is about l30.

3. The printer of claim 1 in which the reciprocal rod actuating means isa pneumatic system responsive to an electrical control circuit.

4. The printer of claim 3 in which the pivot angle is about l20-l30.

S. The printer of claim 3 including a spring means for exerting a linearforce upon the printing arm in a direction opposite to the forwardmotion of said arm.

6. The printer of claim 5 in which the pivot angle is about 120l30.

7. The printer of claim 5 in which said spring means is a spring mountedwithin a hole drilled down the center of said printing arm from the endof said arm opposite said printing plate to said printing arm shaft.

8. The printer of claim 7 in which the pivot angle is about 120130.

1. A printer comprising: reciprocal rod actuating means pivotally fixedat a stationary point; a rod attached at one end to said actuating meansand pivotally attached at the other end to a tongue projecting from theside of a printing arm, said tongue being located at a pointintermediate of the ends of said printing arm; said printing arm havinga printing plate attached to one end thereof; said rod and said printingarm being substantially aligned in one plane but being slightly out ofparallel when viewed perpendicular to said plane when said rod is in itsextended position, the angle between said rod and said arm beingconvergent in a direction toward said tongue; said arm being pivotallysecured to a fixed point intermediate said tongue and the opposite endof said arm; said arm containing a longitudinal slot in which is locateda fixed printing arm shaft, the axis of said shaft being perpendicularto said arm and parallel to the axis of pivot of both said rod actuatingmeans and said tongue, said shaft being located at a point intermediatesaid tongue and the opposite end of said arm; a bearing surface mountedon a fixed bearing mounting shaft, said bearing mounting shaft beingparallel to said printing arm shaft and being positioned between saidrod and said arm at a point intermediate said printing arm shaft and theend of said arm opposite the end on which said printing plate isaffixed; whereby said printing arm is pivotable from an extendedposition, at which said rod is in its extended position, to a partiallyretracted position, at a pivot angle of about 110*140* from saidextended position, in which said arm contacts said bearing surface, andwhereby said arm is movable in a straight line along said bearingsurface to a fully-retracted position; and a printing ink pad in a fixedposition, said position being located so that said printing platecontacts said pad when said arm reaches said fully-extended position. 2.The printer of claim 1 in which said pivot angle is about 120*-130*. 3.The printer of claim 1 in which the reciprocal rod actuating means is apneumatic system responsive to an electrical control circuit.
 4. Theprinter of claim 3 in which the pivot angle is about 120*-130*.
 5. Theprinter of claim 3 including a spring means for exerting a linear forceupon the printing arm in a direction opposite to the forward motion ofsaid arm.
 6. The printer of claim 5 in which the pivot angle is about120*-130*.
 7. The printer of claim 5 in which said spring means is aspring mounted within a hole drilled down the center of said printingarm from the end of said arm opposite said printing plate to saidprinting arm shaft.
 8. The printer of claim 7 in which the pivot angleis about 120*-130*.